The present invention relates to a handling robot control method for use in a multiple chamber type manufacturing system such as for making semiconductors and LCDs in which a plurality of process chambers designed to constitute individual stations or stages are arranged around a single transfer chamber, and a workpiece in the form of a sheet or a thin plate such as a wafer to be worked on and processed in each of the process chambers is transferred by a handling robot from one of the process chambers to another via the transfer chamber.
A multiple chamber type semiconductor manufacturing system constructed as shown in FIG. 1 includes a transfer chamber 1 around which a plurality of process chambers stations 2a, 2b, 2c, 2d, 2e, each comprising a process chamber, and for delivering a workpiece to the outside section of the system workpiece delivery stations 3 are arranged. The inside of the transfer chamber 1 is normally held in vacuum by suitable vacuum equipment.
The transfer chamber 1 is constructed as shown in FIG. 2, having a handling robot A disposed turnably in its central region. Constituting its peripheral wall as a whole, partition walls 5 that are opposed to the process chamber stations 2a, 2b, 2c, 2d, 2e and the workpiece delivering stations 3 are formed with gates 6, respectively, each of which provides an inlet and outlet for a workpiece into and out of each process chamber station. These gates 6 so they may be opened and closed are provided with their respective opening/closing doors (not shown) arranged in opposition thereto, respectively, inside the transfer chamber 2.
For the handling robot A use is typically made of a robot of double arm type, so called xe2x80x9cfrog legxe2x80x9d type, which is constructed as shown in FIGS. 3 through FIGS. 6A and 6B.
As shown, a boss portion B of the handling robot A has a pair of arms 7a and 7b of an identical length each of which is turnable about a center of rotation. It also has a pair of carrier tables 8a and 8b of an identical form, disposed at the opposite sides of the center of rotation or turning. The carrier tables 8a and 8b have their respective bases to each of which respective one ends of a pair of links 9a and 9b having an identical length are connected. The respective one ends of the two links 9a and 9b are connected to each of the two carrier tables 8a and 8b through a frog leg type carrier table posture control mechanism so that the two links may turn completely symmetrically and in opposite directions with respect to each of the carrier tables 8a and 8b. And, one of the two links 9a connected to the carrier tables 8a and 8b is connected to one of the arms 7a while the other link 9b is connected to the other arm 7b. 
FIGS. 4A and 4B show different forms of the frog leg type carrier table posture control mechanism mentioned above. Thus, the respective one ends of the two links 9a and 9b may be connected to each of the carrier tables 8a and 8b through a gear structure comprising a pair of gears 9c and 9c in mesh with each other so that the respective angles of posture xcex8R and xcex8L of the links 9a and 9b with respect to each of the carrier tables 8a and 8b may always be held identical to each other. This permits each of the carrier tables 8a and 8b to be oriented and to be operated in a radial direction of the transfer chamber 1. For the links 9a and 9b to be connected to the carrier tables 8a and 8b, in lieu of the gears a crossed belting arrangement 9d may be employed as shown in FIG. 4B.
FIG. 5 shows a conventional mechanism for moving the arms 7a and 7b to turn independently of each other. The bases of the arms 7a and 7b are each in the form of a ring and are constituted with ring bosses 10a and 10b, respectively, which are positioned coaxially about the center of rotation or turning and supported turnably with respect to the transfer chamber 1.
Inside of each of the ring bosses 10a and 10b, there is arranged a disk boss 11a, 11b coaxially therewith and opposed thereto, respectively. Each pair of the ring boss and the disk boss 10a and 11a, 10b and 11b that are opposed to each other are magnetically coupled together with a magnetic coupling 12a, 12b in the rotary direction.
The rotary shafts 13a and 13b of the disk bosses 11a and 11b are arranged coaxially with each other and are connected to the output sections of the motor units 14a and 14b, respectively, which are in turn supported coaxially with each other and axially deviated in position from one to the other on a frame 1a of the transfer chamber 1.
The motor units 14a and 14b may each be an integral combination of an AC servo motor 15 and a reducer 16 using a harmonic drive (a trade name, the representation which will be repeated hereafter) and having a large reduction ratio in which the output sections of the reducers 16 and 16 are connected to the base ends of the rotary shafts 13a and 13b, respectively. Because the transfer chamber 1 in which the arms 7a and 7b are positioned is to be maintained in a vacuum state, sealing partition walls 17 are provided each between the ring boss 10a and the disk boss 11a and between the ring boss 10b and the disk boss 11b. 
FIGS. 6A and 6B are used to describe an operation of the conventional handling robot A. When the two arms 7a and 7b lie at diametrically opposed, symmetrical positions about the center of rotation as shown in FIG. 6A, the two links 9a and 9b will each have had turned to have its two legs opened at maximum with respect to the carrier tables 8a and 8b. The two carrier tables 8a and 8b will then have been moved towards the center of rotation or turning.
In this state, turning the two arms 7a and 7b in a given direction will cause the two carrier tables 8a and 8b to turn jointly about the center of rotation while maintaining their radial positions. Conversely, turning the two arms 7a and 7b from the state shown in FIG. 6A in opposite directions such as to have them approach each other will cause the one carrier table 8a of the position where the angle made with the arms 7a and 7b is decreasing to be pushed by the links 9a and 9b to move to project radially outwards and thus to be plunged or forced to project into the process chamber of the one of stations 2a, 2b, 2c, 2d and 2e that is adjacent thereto radially outside of the transfer chamber 1 as shown in FIG. 6B.
In this case, while the other carrier table is moved towards the center of rotation or turning, the distance of this movement will be small because of the angles that the arms 7a and 7b are making with the links 9a and 9b. 
While a conventional handling robot A as described having two carrier tables permits them to be used alternately or successively and is expected to achieve an operation and effects of a double arm robot, in reality it has problems as mentioned below.
Specifically, a sequence of processes is predetermined. Feeding a wafer processed in each process chamber station sequentially into each next station permits a wafer that is being or has been processed to remain in each such station. If, then, a processed wafer in a certain station is to be exchanged with an unprocessed wafer, as shown in FIGS. 7 through 11 it is the common practice with the conventional handling robot A first to support the processed wafer W1 on one carrier table 8a, and then to turn the handling robot A to oppose the vacant carrier table 8b (FIG. 7) to a station 2e where the wafer is being exchanged.
Then, the vacant carrier table 8b is forced to move into the station 2e to accept the processed wafer W2 thereon (FIG. 8) and to be conveyed into the transfer chamber 1. Thereafter, the handling robot A is turned by 180 degrees (FIG. 9) to permit the carrier table 8a carrying the unprocessed wafer W1 to be opposed to the station 2e and then to be forced to move into the station 2e (FIG. 10). The unprocessed wafer W1 is thus conveyed into the station 2e while the carrier table that became vacant 8a is retracted into the transfer chamber 1 (FIG. 11).
In this way, each time wafers are exchanged, the handling robot has had to be turned by 180 and as a result has had the problem that it entails a relatively long cycle time for the wafer exchanging operation.
As described in International Patent Application published as WO 97/35690 and filed by the present applicant, there are a second and a third type of handling robots Axe2x80x2 and Axe2x80x3 that can be turned by an angle as small as 45 degrees to enable a processed wafer in a station and an unprocessed wafer in the transfer chamber to be exchanged with each other, thus being capable of shortening the cycle time for a wafer exchange operation.
The second type of handling robot Axe2x80x2 referred to above is depicted in FIGS. 12 through 14. Thus, centrally of the transfer chamber 1, the handling robot Axe2x80x2 has two ring bosses, a first and a second 20a and 20b that are disposed coaxially with each other and lie one above the other in their axial direction. The first and second ring bosses 20a and 20b are supported with bearings (not shown) so as to be each individually rotatable. Each of the ring bosses 20a and 20b has in its inside a disk boss 21a, 21b juxtaposed therewith, respectively, which lie one above the other in their axial direction. The disk bosses 21a and 21b are supported through bearings (not shown) so as to be each individually rotatable on the frame of the transfer chamber 1.
Each pair of the ring boss 20a and the disk boss 21a, the ring boss 20b and the disk boss 21b are magnetically coupled together by a magnetic coupling 22a, 22b in their respective rotary directions. A sealing partition wall 23 is provided between the ring bosses 20a, 20b and the disk bosses 21a, 21b so that the transfer chamber 1 is maintained in a vacuum state.
The disk bosses 21a and 21b have at their respective axial center portions their respective rotary shafts 24a and 24b disposed coaxially with each other. Of these two rotary shafts, the first rotary shaft 24a is hollow into which the second rotary shaft 24b is inserted to rest therein. The first and second rotary shafts 24a and 24b are connected each via a coupling mechanism such a timing belt to the output shafts 26a and 26b of a first and a second motor unit 25a and 25b, respectively.
For each of the motor units 25a and 25b, use may be made of either a combination of a servo motor and a reducer or a motor alone. It is important that each of the output shafts. 26a, 26b of the motor units 25a and 25b have an output reduced at a very large redaction ratio and controlled as to the direction of rotation, i.e., normal rotation or reverse rotation. It is also important that a speed ration of the coupling mechanism for connecting the output shaft 26a to the rotary shaft 24a and a speed ratio of the coupling mechanism for coupling the output shaft 26b to the rotary shaft 24b are identical to each other.
The first ring boss 20a has on side surfaces thereof a first and a second arm 27a and 27b projecting radially outwards thereof. The second ring boss 20b has on a side surface thereof a third arm 27c projecting radially outwards thereof. A leg column 27e is mounted on a top surface of the second ring boss 20b and has on its top a fourth arm 27d extending radially outwards thereof. These arms have their respective tuning fulcrums on the upper surfaces of their respective ends.
These arms 27a, 27b, 27c and 27d have an identical turning radius A for their respective turning fulcrums. The first and fourth arms 27a and 27d have their respective turning fulcrums that are positioned vertically identically to each other. The second and third arms 27b and 27c have their respective turning fulcrums that are positioned vertically identically to each other on a plane which lies below those of the first and fourth arms 27a and 27d. 
Turnably connected to the respective ends of the arms 27a, 27b, 27c and 27d on their respective turning fulcrums are ends of a first, a second, a third and a fourth link 28a, 28b, 28c and 28d, respectively, each of which has a length greater than the length R of each of the arms. And, the first and fourth links 28a and 28d have the first carrier table 8a connected thereto via a frog leg type carrier table position control mechanism on their end lower surfaces. Also, the second and third links 28b and 28c have the second carrier table 8b connected thereto via such a frog leg type carrier table position control mechanism on their end upper surfaces.
Then, the first carrier table 8a lies to assume a so called standby state thereof where both the first and fourth arms 27a and 27d are aligned in their diametric directions. Likewise, the second carrier table 8b is also assuming a standby state thereof when the second and third arms are aligned in their diametric directions. And, the two carrier tables 8a and 8b in their respective standby states are seen as deviated in position from one to the other in a rotary or turning direction of the ring bosses, this (shown in FIG. 14) being a standby state of the handling robot. Turning each ring boss from this state will cause each carrier table 8a, 8b to be moved back and forth, or the handling robot will be permitted to be turned or swung in this standby state. Then, the two carrier tables 8a and 8b, not overlaping each other in the rotary direction, are positioned vertically identically to each other as shown in FIG. 13. It should also be noted that the end of the first arm 27a is curved outwards so that it may not be interfered by the end of the third arm 27c. 
The handling robot Axe2x80x2 constructed as so far described can perform an operation that is to be described in FIGS. 15 through 18. Thus, in the state in which one of carrier tables 8a has an unprocessed wafer W1 carried thereon, the handling robot in its standby state will be turned as a whole (FIG. 15) to position a vacant carrier table 8a, the carrier table not having any wafer at all carried thereon in front of a process chamber station 2e having a processed wafer W2 (FIG. 15).
Then, the vacant carrier table 8b will be moved into the process chamber station 2e to accept the processed wafer W2 thereon and to convey it out (FIG. 16). Thereafter, the handling robot will be turned as a whole in its standby state and continue to be turned until the carrier table 8a having the unprocessed wafer W1 carried thereon reaches in front of the process chamber station (FIG. 17). The angle of turning that the handling robot must then make as a whole needs only to correspond to a difference in angular position between the carrier tables 8a and 8b and is, for example, about 45 degrees.
The carrier table 8a having the unprocessed wafer W1 carried thereon will be moved to project into the process chamber station 2e and to set it in position within the process chamber station 2e (FIG. 18). Subsequently, the handling robot will retract the carrier table 8a now vacant into a transfer chamber 1 side and will then be turned as a whole to move the carrier table 8b until the processed wafer W2 reaches in front of the process chamber station 2a for a next processing. The operation described will be repeated.
On the other hand, the handling robot Axe2x80x3 referred to above is depicted in FIGS. 20 through 22. In these Figures, reference numeral 30 denotes a turn table turnably supported on the frame of the transfer chamber 1. At the turning center of the turn table 30, a drive shaft 31 is supported rotatably with respect to the turn table 30. And, the turn table 30 is adapted to be driven to turn normally and reversely by a first motor unit 32a fastened to a frame of the transfer chamber 1 while the drive shaft 31 is adapted to be driven to rotate normally and reversely by a second motor unit 32b fastened to a turn table 30.
A first and a second robot link mechanism B1 and B2 are provided at the opposite sides of the axial center of the drive shaft 31, and each of which comprises a drive link mechanism 33, 34 that is here constituted by a parallel linkage. The first drive link mechanism 33 comprises a driving and a driven link 33a and 33b extending in parallel to each other and a coupling link 33c that connects the ends of these two links 33a and 33b together. Also, the second drive link mechanism 34 comprises a driving and a driven link 34a and 34b extending in parallel to each other and a coupling link 34c that connects the ends of these two links 34a and 34b together.
And, the respective driving links 33a and 34b of the two drive link mechanisms 33 and 34 have their respective bases fastened and thereby connected to the drive shaft 31. Also, the driven links 33b and 34b through their respective bases are pivotally supported on the turn table 30 so that lines passing through their respective bases and the drive shaft 31 may orient relative to each other with an angle xcex1 (60 degrees) about the center of rotation (turning) of the turn table 30. The respective coupling links 33c and 34c of the two drive link mechanisms 33 and 34 have at their respective two opposite ends, support shafts 35a and 35b; and 36a and 36b with gears 37a and 37b in mesh with each other; and gears 37c and 37d in mesh with each other, the gears having an identical number of teeth. Of those support shafts, the support shafts 35a and 36a lying at the respective ends of the driving links 33a and 34a are integrally connected thereto, respectively while the support shafts 35b and 36b are freely rotatable relative to the driven links 33b and 34b, respectively.
Connected respectively to the end sides of the drive link mechanisms 33 and 34 for the first and second robot link mechanisms B1 and B2 are a first and a second driven link mechanism 38 and 39 each of which is again constituted by a parallel linkage that is identical in size to the parallel linkage constituting each drive link mechanism 33, 34. The first driven link mechanism 38 comprises a driving and a driven link 38a and 38b extending in parallel to each other and a coupling link 40a that connects the these two links 38a and 38b together. Also, the second driven link mechanism 39 comprises a driving and a driven link 39a and 39b and a coupling link 40b that connects these two links 39a and 39b together.
Of base ends of these links, the base ends of the driving links 38a and 39a are integrally joined with the support shafts 35b and 36b at the driven link 33b and 34b sides of the first and second drive link mechanisms 33 and 34, respectively while the base ends of the driven links 38b and 39b are rotatably connected to the support shafts 35a and 36a, respectively.
And, the carrier tables 8a and 8b are integrally connected to the links 40a and 40b at the end sides of the driven link mechanisms 38 and 39, respectively. Because of each linkage configuration of the two driven link mechanisms 38 and 39 and the configuration of the two carrier tables 8a and 8b, the two carrier tables 8a and 8b are allowed to take a vertically identical position as shown in FIG. 22. Also, the two carrier tables 8a and 8b have their respective base ends ensured not for them to interfere with each other.
Also, the two carrier tables 8a and 8b are here arranged to lie on and be in alignment with the extensions of the links 40a and 40b at the end sides of the two driven link mechanisms, respectively. Consequently, the two carrier tables 8a and 8b stand angularly deviated in position from each other about the center of turning of the turn table 30 by the angle xcex1 mentioned previously. In FIG. 22 there is also shown a magnetic fluid seal 41.
An explanation will now be given of an operation of the third type of handling robot Axe2x80x3 constructed as so far described.
In the standby state shown in FIG. 21, driving the second motor unit 32b to rotate normally or reversely to rotate the drive shaft 31, e. g., clockwise will cause the respective driving links 33a and 34a in the drive link mechanisms 33 and 34 for the first and second robot link mechanisms B1 and B2 mechanisms 33a and 34a to turn clockwise as a whole.
This will, as shown in FIG. 20 , cause the first and second driven link mechanisms 38 and 39 through the joint action of the gears 37a, 37b, 37c and 37d to turn counter-clockwise, permitting the carrier table 8a on the first robot link mechanism B1 to move forwards or advance and the second carrier table 8b on the second robot link mechanism B2 to be moved back or retracted. The carrier tables 8a and 8b will be moved forth and back in the directions defined by the angles xcex11 and xcex12 that represent the respective angles of the angular deviation of the respective bases of the driven links 33b and 34b of the first and second drive link mechanisms 33 and 34, respectively. The angles xcex11 and xcex12 make the angle xcex1.
Conversely, driving the drive shaft 31 reversely or counter-clockwise will retract the carrier table 8a on the first robot link mechanism B1 in the angular direction defined by the angle xcex11 while the carrier table 8b on the second robot link mechanism B2 will advance the carrier table 8b on the second robot link mechanism B2 in the angular direction defined by the angle xcex12.
In the standby state shown in FIG. 21, driving the first motor unit 32a will turn the turn table 30 to cause the first and second robot link mechanisms B1 and B2 to turn jointly.
Being arranged to permit a pair of carrier tables to be advanced or moved to project and retracted in the angular directions of 45 degrees or 60 degrees, it is seen that the second and third types of handling robot Axe2x80x2 and Axe2x80x3 so far described reduce the turning angle for the robot system to turn as a whole where wafers are to be exchanged, compared with the first handling robot A described earlier that entails a phase deviation of 180 degrees. However, the reduction still require the entire robot to be turned by as much as 45 degrees or 60 degrees where wafers are to be exchanged if such angles are considered small. And, with the second and third handling robots Axe2x80x2 and Axe2x80x3 as with the first type of handling robot A, the entire robot system must still be turned only after a carrier table advanced into a process chamber station 2e is retracted into the transfer chamber 1 and then brought into its standby state. Thus, a loss of time remains to be involved in the operation in which the carrier table are being advanced or moved to project and retracted. As a consequence, the reduction of the cycle time still remains at most as much as the angle by which the handling robot needs to be turned is simply reduced to 45 degrees or 60 degrees from 180 degrees.
Created in the foregoing taken into account, the present invention has for an object thereof to provide a handling robot control method that permits the cycle time of an entire robot handling operation for a handling robot both to be turned and to be advanced or moved to project and retract or to move forth and back the carrier tables to be shortened.
Created with the foregoing taken into account, a handling robot control method is provided in accordance with the present invention in a certain aspect thereof for a handling robot disposed in a transfer chamber having a plurality of process chamber stations arranged around it in communication therewith via respective gates, the robot having a first and a second carrier table that are deviated in turning angular position from one to the other about a center of turning, the robot performing an operation to move the said first and second carrier tables to turn jointly in the said transfer chamber and also an operation to move the said first and second carrier tables individually either to project through said gate into said process chamber station or to retract into the said transfer chamber, which method comprises: overlapping said operation to move the said first and second carrier tables individually either to project or to retract with said operation to move the said first and second carrier tables to turn jointly.
According to the handling robot control method described above, it can be seen and should be appreciated that as a result of overlapping an operation of moving the carrier tables individually to project or to retract with an operation of moving the two carrier tables to turn jointly, the cycle time of an entire robot handling operation for a handling robot both to be turned and to be moved so as to move the two carrier tables individually either to project or to retract may be shortened.
It is preferred that the said carrier tables in the said overlapped operations follow a path of movement that does not pass a point of intersection of a path of movement along which to move the said first and second carrier tables individually either to project or to retract and a path of movement along which to move the said first and second carrier tables to turn jointly, but that follows a short-cut curve.
Also, the said operation to move the said first and second carrier tables individually either to project or to retract that is performed while overlapping with the said operation to move the said first and second carrier tables to turn jointly is performed so as not to interfere with the said gate.